The present invention relates generally to a printers and, more particularly, to shuttle head printers.
In shuttle head printers, such as dot-matrix printers, inkjet printers and bubble-jet printers, the print head assembly travels across a print media such as a sheet of paper or a mail piece, marking the media such as by rendering ink on the media one band at a time. The printer advances the print media under the print head assembly after printing a band in preparation for the next band. The print head assembly then traverses back across the print media, rendering the next band. The back and forth movement interspersed with media motion continues until the printing on the media is completed. One of the factors determining the overall throughput of the printer is the speed at which the print head assembly is able to traverse the print media. A typical inkjet shuttle head printer includes a print head assembly that consists of plastic print head holder, which secures one or more print cartridges. Two metal bearings are molded into the holder for guiding the print head assembly along a polished steel guide shaft. A ribbon cable assembly is connected to the print head assembly using a set of contact points for providing electrical connections with the print cartridges.
As the printer is used over a period of time, debris such as dust resulting from the media handling and printing accumulates on the guide shaft. The dust is also mixed with the lubricants leached from the bearings. When the guide shaft becomes dirty, it slows down the print head speed and significantly reduces the overall throughput of the printer. When that happens, the guide shaft must be cleaned. Some printers include a shuttle motor test feature, but do not test for a print shaft contamination condition. Certain printers rely on technicians to perform maintenance after a failure caused by print shaft contamination. Yet other printing systems reduce throughput due to the contamination condition without any warning or feedback to the operator.
Accordingly, there is a need for a printing system that is capable of testing for a print shaft contamination condition and for providing a warning to a printer operator.